Method And Apparatus For Antenna Tuning - Patent 8131232

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Method And Apparatus For Antenna Tuning - Patent 8131232 Powered By Docstoc
Description: 1. Field of the Invention The present invention relates generally to the field of wireless communications, and more particularly, to a method and apparatus for antenna impedance matching in a wireless communication device. 2. Description of the Related Art It is well known that impedance matching is required to optimize energy transfer from a source to a load in radio-frequency circuits. In radio communication devices such as wireless transceivers, there are several places within the systemrequiring impedance matching, but one of the most challenging is the connection between a transmitter as a source and an antenna as a load. A poor impedance match in this part of a transceiver system results in the inefficient transfer of power to theantenna, and thus requires more power, for example from a battery in a portable system, in order to achieve a given level of radiated power needed for a robust communication link. A similar situation occurs between an antenna as a source and a receiveras a load, but mismatch in this path, while resulting in poorer received signal quality, does not have as direct an impact on power consumption of the transceiver. A parameter commonly specified to indicate the degree of mismatch is the voltage standingwave ratio (VSWR). An ideal VSWR of 1.0:1 indicates no mismatch (perfect matching) and no reflected power from a load. Antenna matching is becoming more challenging in modern mobile wireless devices, which are supporting a growing range of services and frequencies beyond cellular telephony, including wireless local area networks (WLAN), personal area networkssuch as Bluetooth, mobile television protocols, and Global Positioning Systems (GPS). Miniature antennas are being asked to cover frequencies ranging from 824 to 2170 MHz and more in order to perform all these functions. Simultaneously, smallerbatteries and longer battery life are desired in increasingly miniaturized, handheld packages, in which the antenna must be fit into a